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MG MGB Technical - Running-in.

A persistent bottom end knocking now sees me undertaking an engine rebuild on my son's Mk1 MGB GT (BRG 1966, one previous owner. Very nice car). Running-in time is not too far away (he says hopefully). In the dim and distant past I remember being advised that on completion of the rebuild to fill with something like 20/30 oil. Also, in order to properly bed the new piston rings, once the engine is running smoothly on first start up, the car should be driven in the highest gear possible at approximately one quarter revs. Then after a mile or so the revs should be increased to three quarters max for another mile. Was this sensible advice in the past and if so is this process still used today? Any thoughts or advice appreciated.
Chris
Chris Woodfield

Use designated "running in oil" or a running in additive. The important items to "bed in" are the new cam and followers. On first start up the engine should be held at approx 2000 rpm for 15 minutes. As for how to drive the car, my understanding was that revs were not the problem but it was important NOT to let the engine struggle in a high gear at low speeds. Doing this puts a lot of pressure on the big ends and main bearings which also need a nurtured run-in.
Allan Reeling

Chris,

What Allan wrote, and then I also pinched this bit from the MG Experience web site written by Hap Waldrop of Acme Speed Shop in South Carolina (2010).

Hap Waldrop
Greenville, SC, USA

I send out a instruction sheet with the engines I build.

With the spark plugs removed, and the ignition disabled.
Fill the rear oil fitting on the passenger side of the block, this is normally a oil exit line, so if you turn via a wrench or socket counter clockwise you will pull oil into the oil pump, with the line still not attached turn the engine over via the starter until you just see oil coming out of this fitting, now you can hook up the oil line Turn the engine over via the starter and look for the oil pressure gauge to start to show pressure, this may take a few minutes, give the starter a break if it takes too long, then go at it again.

Once you see the oil pressure at the gage, you are now ready to install the plug wires and actually crank the engine for the first time. Now at this time I like to be at the carbs, and have someone operation the ignition switch, once the engine fires, adjust your idle screw to make the idle 2000 rpm's, you need to run the engine at 2000 rpm's for 20 minutes to be the new cam and lifters in, if the temp start to rise, shut it down, it does not matter if you get your 20 minutes at 2000 rpm's in one or more heat cycles. Also it's a good idea to have your timing light ready to go, so you can get the timing close, later you can dial it in. Once you cranked the engine and run it a couple of heat cycles, it's now time to re-torque the head and adjust the valves don't put this off too long, the head nut furthest form the center will probably need the most re-torque, so don't delay doing this, it need to be done soon. When I first crank the engine, I normally don't have the radiator cap on, this will allow the system to work out any air pockets and you to add to the radiator, then you can cap the radiator as the engine runs and before it reaches full operating temps. Its big time important to keep a close watch on temps and pressures, watch them like a hawk, if you see anything critical, immediately shut the engine off. Once you have your 20 minute of cam and lifter bedding adjust your idle.

As you go for your first drive, don't baby the engine, I'm not saying to redline it, just don't putt around at rpm's slightly above idle, run the engine up and down the rpm range, stay below 5000 rpm for the first 100 miles. Change the oil and filter in the first couple hundred miles, and no later than 500 miles.

Check your fluid level often during the break in process, if you have a dry oil system then it got to get into all the line and the oil cooler, if you can pre fill a dry oil cooler when you install it.


Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


LC

Alan/LC

That's really useful information. Many thanks. Still plenty of things to do beforehand but I'll put the points you raise into practice. Glad I didn't just rely on my memory.

Regards
Chris
Chris Woodfield

I would recommend a quality running in oil as it is all too easy to cause arrested running in with modern oils, even cheap ones. We are moving on to Joe Gibbs Break in Oil for all our engines.
Peter
Peter Burgess Tuning

Peter
Many thanks for the advice. I'll seek out that brand.
Regards
Chris
Chris Woodfield

Miller Oils sell a specific "classic car" running in oil which I have used before with success. Available from lots of suppliers like Demon Tweeks.
http://www.demon-tweeks.co.uk/performance/engine-oil/millers-oils-classic-running-in-oil-mineral-based
Mike Howlett

Most of the good oil manufacturers do "running-in" oil. Castrol, Morris etc.
Allan Reeling

Mike/Allan
More information. That's great. many thanks.
Regards
Chris
Chris Woodfield

Hopefully I'll soon be running-in my rebuilt V8, and have Millers from David Manners ready and waiting. I had quite a job tracking that down even with Googling.
paulh4

Paul
Thanks for the David Manners tip, his store is not too far away. Good luck with the V8.
Regards
Chris
Chris Woodfield

Thanks, after a lot of messing about it's been nine months so far. Hopefully getting it back to reinstall next week, the body is sitting waiting for that before it's final top coats.
paulh4

Paul, where are you having it painted and with what type of paint?

(apologies for thread drift!)
Dave O'Neill 2

One Stop Body Shop in Lye - 07815 317 038, Chris. Two-pack in the engine bay for its hard wearing, acrylic colour coat and clear coat externally. Discussed every step and various alternatives with me along the way. He does panel work and mechanicals as well, less happy with electrics though :o)

So far I have been very happy with them, Chris has had no problem with me messing around with the car while it's been there. He's also been very patient with the engine delays (probably because he recommended him to me ...), on a couple of occasions he has been on the verge of having to top-coat it to have some paying work, but something else has always come in to allow it to be delayed a bit longer.
paulh4

Asking for advice on 'running in' now seems to have been a little premature. The engine rebuild has thrown up a few issues and slowed down the process. A re-bore was required due to some minor cylinder wear and is currently being sorted at a local engineering works. Slightly more troublesome is the discovery of a small cylinder head crack between the wall of one exhaust/inlet valve chamber and a water flow hole. The head is the early type (48G318/12H1326 manufactured in March 1966). The car has matching numbers all round so in this instance, with originality being high on the wish list, the intention is to have the head repaired. This is is going to take some time and I suspect more than a little of the hard earned folding stuff. The head did receive attention some years ago having been converted to take unleaded fuel. On stripping the head this time I noticed that only the four inlet valve stem guides appear to have seals and these seem to be of a revised design. Is this configuration correct or should the exhaust guides also be sealed? Any thoughts would be appreciated.
Chris
Chris Woodfield

Inlets only sealed, as they help prevent oil being sucked down the guides when the pistons are on their intake stroke. Doesn't happen with exhaust.
paulh4

I had considered that might be the reason but confirmation and an explanation by the experts is very satisfying and always worth while.
Many thanks
Chris
Chris Woodfield

For the best possible cylinder head work you should speak to Peter Burgess in Alfreton. There is no better. Ring him on 01773 520021
Mike Howlett

I agree Mike. Peter has a terrific reputation.
Chris Woodfield

This thread was discussed between 06/06/2017 and 29/06/2017

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